an agricultural municipio of 12,000, is 230 miles south of Monterrey in a region of heavy out-migration to Monterrey and was selected as representative of this type of community.*
Partly to balance somewhat the emphasis given to Latin America and Mexico, and also because it is an impressive study in its own right, the study of rural-urban migration in Ghana as recently reported by Caldwell (12) will be given special attention. His study fits into the orientation of this article because his "urban" designation includes the eight largest cities in Ghana. There are important differences in method between the Mexico and Ghana investigations and substantively there are phenomena found in one country and not the other,' but I hope to show that there are also similarities in migratory selectivity of these two countries.
The strategy I have followed is to present propositions (in italics) that bear upon one or another aspect of migrant selectivity. In most cases the available evidence either is so meager or so contradictory that the proposition must be considered as tentative. The advantage of the prepositional format is that it is stated in testable terms. Although a comprehensive theory of migrant selectivity is not available at this time, it is possible to begin to accumulate the propositions that would enter into such a theory. I have not, however, attempted to include all conceivable or even relevant propositions.
ORIGIN OF MIGRANTS TO LARGE CITIES IN DEVELOPING COUNTRIES
The selectivity of migrants to large cities obviously will be much affected by the kinds of communities from which they originate. Migrants may be drawn from the whole range of settlements in a representative fashion, or
*The 1965 Monterrey Mobility Study was a project jointly sponsored by the Ccntro de Investigaciones Economicas of the Facultad de Economia, Universidad de Nuevo Leon and the Population Research Center of the Department of Sociology at the University of Texas at Austin. The research at both institutions was facilitated in part by grants from the Ford Foundation. The directors of the project are Jorge Balan and Elizabeth Balan (formerly of the Universidad de Nuevo Leon) and Harley L. Browning. The 1967 survey of Cedral was carried out by the Population Research Center by the same directors and again with Ford support.
The Monterrey study has been reported in a number of articles and those pertinent to migration are (13-20).
tin Mexico the principal investigation was metropolitan Monterrey, with 1,640 males aged 20 to 60 interviewed, while rural Cedral, with 390 males aged 15 to 64, was subsidiary. In Ghana CaldwelTs main concern was with the rural population. He obtained information in 1963 from 1,782 households (13,776 persons) in a reasonably representative sample of villages. He supplemented this with 585 households (3,167) in four cities, with 68 percent of the total obtained in Accra-Tema, Ghana's largest city. In the rural interview information was obtained about persons absent from the village. For further methodological details of the two studies see Caldwell (12, Ch. 1) and Balan, et al. (1 3, Ch. 1). Substantively, Ghana differs from Mexico in the predominantly male rural-urban migration, in the multilingual character of the society, in the existence of polygamy, and
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